Self-adjusting rocker arm



Dec. 5, 1950 s. w. HALL 2,532,905

SELF-ADJUSTING ROCKER ARM Filed Feb. 1, 1949 Patented Dec. 5, 1950 UNITED STATES PATENT OFFICE- SELF-ADJUSTING ROCKER ARM Sidney Hall, San Antonio, Tex. Application February 1, 1949, Serial No. 73,952

9 Claims. (01. 74-519) This invention relates to a valve operating mechanism and more particularly to a self-adjusting rocker arm especially intended for use with internal combustion engines of the overhead valve type.

An object of my invention is the provision of an improved rocker arm which will enable reciprccating action to be transmitted quietly and efiiciently.

Another object of the invention is to provide a rocker arm assembly wherein perfect adjustment will be maintained automatically under changing conditions due to expansion, contraction and wear of the parts.

Still further advantages of my present invention are its simplicity of construction and its ability to be substituted for the conventional rocker arms now in use without involving changes in. the present design of the other parts of an engine assembly.

To these and other ends my invention comprises further improvements and advantages as will be further described in the accompanying specification, the novel features thereof being set forth in the appended claims.

In the drawings:

Figure 1 is a perspective view of a rocker arm embodying my invention and shown mounted on an engine bearing shaft.

Figure 2 is a top plan View of the device.

Figure 3 is a fragmentary top plan view of the rocker arm with its segments separated to illustrate the cooperating angular bearing surfaces on the two parts of the arm.

Figure 4 is a top plan view of a modified form of the pressure springs.

Figure 5 is a side elevation of the rocker arm shown in Fig. 4.

Figure 6 is a side view of one of the fingers showing the cut out portion on the inner face of the hub portion, as seen when viewed along the line 6-6 of Fig. 3.

Similar reference numerals, in the several figures, indicate similar parts. 7

The means commonly used for transmitting movement between the inlet and exhaust valves and the cam shaft in an over-head valve type internal combustion engine consists of one-piece rocker arms connectingthe upper ends of the valve stems and the cam shaft push rod which are pivotally supported therebetween by a horizontal bearing shaft. With this conventional arrangement, the power transmitting mechanism must be set with a predetermined clearance or gap between two elements of the assembly to allow for the inevitable expansion of parts when the engine becomes heated. Without the presence of this slack setting, the expansion of the push rod and valve stem would decrease the extent of the movement of the valves and effect the intake and exhaust strokes of the engine piston resulting in a reduction in output efficiency of the engine.

On the other hand, owners of automobiles equipped with these so-called over-head valve tappets are constantly aware of additional engine noise due to repeated contact between the spaced elements in the assembly. Reduction or complete removal of such undesirable noise is a primary endeavor in the design of automotive engines.

In answer to this difficulty confronting the automotive industry, I have devised a two-piece rocker arm as shown in the drawings. As seen in Figs. 1 and 2, the rocker arm consists of two parts, namely, a valve stem contact finger Ill and a push rod contact finger H.

The finger H] projects horizontallyas indicated at l2 and is stiffened with a longitudinal flange l3 on its upper side. It is pivotally secured to the horizontal bearing shaft IQ of the engine by means of a hollow hub I5 which extends laterally beyond one of its edges to form a boss 16 and on the lower surface of its free end is a shallow circular boss l! which acts as the contact surface for engagement with the end of a valve stem.

The second or companion finger l I comprises a bar having a similar hub 18, as above described for finger ID, for supporting it on the shaft [4. The finger H is substantially rectangular in cross-section and is formed with a circular enlargement H3 at its outer free end which contains a threaded aperture through which a push rod adjusting screw 20 passes and is held in place by-a lock nut 2|.

Separate rings 22 (Fig. 5) of suitable wearresistant metal are afiixed within the hollow hubs of the two fingers and serve as suitable bearing surfaces for the rocker arm parts when they are mounted on the shaft [4.

As best seen in Figs. 3 and 6, the adjacent or -proximate ends of the hubs of the fingers are face 24 (shown dotted in Fig. 3) and thus pre sents offset parallel surfaces 25 and 26.

From the drawing it will be understood that with a similar segmental portion removed from the hub of finger ll, surfaces 21, 28 and 29 are formed which are respectively symmetrical to the above mentioned surfaces 23, 25 and 26. Thus with complementary adjacent faces the members I0 and I I will mesh as shown in Fig. 2.

An important feature of my invention lies in the fact that the opposing bearing surfaces 23 and 21 of the finger units are so machined as to form a slight angle with the axis of their respective bearing hubs and consequently to that of the bearing shaft l4. The angle of inclination is preferably six degrees. This may be varied, but I have determined in practice that to insure best results in self adjustment, such variance should be kept to a low angle.

Coil springs 30 and 30 which are standard equipment on the bearing shaft of many makes of over-head valve engines, using the conventional one-piece arm, will be located at opposite sides of my two-piece rocker arm, as shown in Fig. 1. ends by the brackets 31 which support the hearing shaft throughout its length. The inner ends of the springs abut the bosses l6 and I8 respectively and apply a lateral force to the two halves of the arm permitting a wedging effect of the inclined surfaces 23 and 2'! when expansion or contraction occurs in the metallic parts of the rocker arm assembly. This lateral sliding action between the parts of the arm keeps the assembly in perfect adjustment at all times.

In view of the fact that there are some overhead valve type engines that do not use coil springs around the rocker arm bearing shaft, I have shown a modified form of my invention wherein an alternate means for applying lateral force to the two halves of the arm is provided. The finger members [9 and H of the rocker arm, shown in Figs. 4 and 5, are constructed similarl to the members H! and I I previously described. However, in the upper and lower surfaces of each of the hub members [6 and I8 there are drilled small holes into which are inserted tightly fitting vertical pins 32. A short coil spring 33 connects the two upper pins and a similar spring 34 is likewise hooked between the lower pins. This arrangement of parallel springs in effect produces a result similar to that afforded by the coil springs 39 and 36 ordinarily used.

In the initial setting operation of the rocker arm the adjusting screw 26 on one end is screwed down on the push rod until the boss I? on the other end engages the valve stem and the angular bearing surfaces 23 and 27 are in contact. The adjusting screw is then turned down slightly more until the separate portions of the arm separate laterally and there is a visible clearance between the surfaces 25 and 29 and between surfaces 26 and 2 8.

This original setting is made while the engine is cold and as the engine warms up and the push rod and valve expand, the opposing surfaces 23 and 21 are forced to slide in opposite directions againstthe tension of the holding springs. Since the bearing surfaces 23 and 27 are inclined the slight separation of the two halves decreases the effective lengthof the rocker arm in accordance with the combined expansion of the push rod and valve stem and the two parts of the arm themselves.

These springs are retained at their outer When the engine is allowed to cool, the rod and stem accordingly contract and relieve the pressure on the rocker arm. This allows the coil springs to force the arm halves inwardly once again to produce a wedging effect and thus increase the effective length of the rocker arm. This automatic adjustability of the rocker arm obviates the necessity of providing a tappet clearance for the valves in the engine assembly. With this gap absent from the system, the source of the noise characteristic of over-head valves is removed.

From the foregoing description of the present invention it will be seen that I have devised a simply constructed two-piece thermo adjustable rocker arm which will adjust itself in accordance with the temperature changes occurring in the connected elements. This permits a continuous and tight fitting connection from the source of power to the engine cam shaft at all times and allows the engine to efficiently operate with a quietness not possible with the use of conventional rocker arms.

While a preferred form of the invention has been shown and described, it will be understood that variation in details of form may be made without departure from the invention as defined in the appended claims.

I claim:

1. A device for transmitting reciprocating motion comprising a two-piece rocker arm adapted to be mounted on a shaft, opposing bearing surfaces on each of the arm pieces, said surfaces being inclined to the axis of said shaft and means acting laterally on the arm pieces to yieldingly hold said inclined surfaces in engagement.

2. A self-adjusting rocker arm comprising oppositely disposed contact fingers, said fingers being mutually disconnected, a hollow bearing hub on each of said fingers for receiving a transverse shaft, opposing contact surfaces on each of said fingers, said surfaces being inclined to the axis of said hubs and means acting laterally on the fingers to resiliently move said fingers to bring their inclined surfaces together.

3. A self-adjusting rocker arm comprising oppositely disposed contact fingers, said fingers being mutually disconnected, a hollov. bearing hub on each of said fingers for receiving a transverse shaft, complementary segmental recesses in the adjacent faces of said hubs, opposing contact surfaces on each of said fingers, said surfaces being inclined to the axis of said hubs and means acting laterally on the fingers to resiliently move said fingers to bring their inclined surfaces topositely disposed contact fingers, said fingers being mutually disconnected, a hollow -bearing hub on each of said fingers for receiving a transverse shaft, opposing contact surfaces on each of said fingers, said surfaces being inclined to the axis of said hubs, coil springs surrounding said shaft at each side of said rocker arm and acting laterally on said hubs to press the contact fingers together. 6. A device for transmitting reciprocating motion comprising a two-piece rocker arm adapted to be mounted on a shaft, opposing bearing surfaces on each of the arm pieces, said surfaces being inclined to the axis of said shaft, and means connecting the arm pieces to resiliently hold said pieces in lateral engagement.

7. A self-adjusting rocker arm comprising oppositely disposed contact fingers, said fingers being mutually disconnected, a hollow bearing hub on each of said fingers for receiving a transverse shaft, opposing contact surfaces on each of said fingers, said surfaces being inclined to the axis of said hubs, and means connecting the contact fingers to resiliently hold said fingers in lateral engagement.

8. A self-adjusting rocker arm comprising oppositely disposed contact fingers, said fingers being mutually disconnected, a hollow bearing hub on each of said fingers for receiving a transverse shaft, opposing contact surfaces on each of said fingers, said surfaces being inclined to the axis of said hubs, pins projecting from the periphery of each of said hubs and springs connecting fingers, said surfaces being inclined to the axis of said hubs, means surrounding said shaft and acting laterally on said rocker arm to resiliently hold said contact fingers together.

' SIDNEY W. HALL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date go 1,362,709 Lee Dec. 21, 1920 1,801,215 Wilson Apr. 14, 1931 1,846,263 Kull et a1 Feb. 23, 1932 

